1. Field of the Invention
The present invention relates to a drive force adjustment apparatus.
2. Description of the Related Art
A drive force adjustment apparatus of a related art, which adjusts distribution of drive force to the left and right wheels of a vehicle, has been known. In the drive force adjustment apparatus, a drive force adjustment mechanism is provided along with a differential gear between the left and right drive wheels, and a drive force distribution state is controlled by controlling actuation of the drive force adjustment mechanism. Such a configuration has been known as the drive force adjustment mechanism, which is provided with two gear mechanisms for further increasing or further decreasing the velocity of one wheel of the left and right wheels than that of the other wheel and a motor for generating a difference in torque between the left wheel and the right wheel by distributing torque to the left and right wheels. One example of such a related art is disclosed in JP-A-2007-177916.
However, in the drive force adjustment mechanism according to the related art disclosed in JP-A-2007-177916, there may be a case where a carrier supporting planetary gears always rotates in the reverse direction with respect to a case of a differential gear and an output shaft, depending on the number of teeth of respective gears in two gear mechanisms. In this case, there is a problem that agitation resistance in the interior of a casing of the drive force adjustment apparatus increases to resultantly increase the traveling load.
In addition, there may be a case where the reduction ratio of motor torque becomes less than 1, depending on the number of teeth of the respective gears of the two gear mechanisms. In this case, there is a problem that a motor is large-scaled and the weight of the drive force adjustment apparatus increases since a motor which is able to generate a maximum torque greater than a desired difference in torque between the left wheel and the right wheel, must be used.